The invention relates an illumination device for the rear license plate of a motor vehicle.
Such generally known illumination device consists of a rear, body wall section as a carrier wall bearing the license plate and a wall section adjacent to the carrier wall as a projection projecting with an approximately horizontal surface rearward above the license plate. A body wall section forming a top wall abuts the projection in the upward direction.
At least one aperture with a switchable light source disposed above is provided in the projection, wherein the aperture is covered by a transparent lens. The lens covers with a peripheral overlapping edge a contact edge surrounding the aperture from below and is fastened in contact therewith. A pivoting attachment of the lens for mounting in the aperture is well known.
The projection is designed such that the contact edge of the aperture is opaque. Accordingly, the overlapping edge of the lens is not illuminated by the switched-on light source and is therefore so dark that it practically does not contribute to the illumination of the license plate.
The situation is similar when the “aperture” is formed by a downwardly open lamp housing, which is suitably covered by a lens from below, wherein the contact edge is then formed by the lamp housing. This case shall also be included in the term “aperture”.
Detailed regulatory requirements exist for such an illumination device for the rear license plate of a vehicle, in particular with regard to the angle of incidence of the light and the luminance to be maintained by vehicle manufacturers (Official Journal of the European Union L/35 dated 31.01.2009, Rule No. 4 of the Economic Commission of the United Nations for Europe—uniform requirements concerning the approval of illumination devices for the rear license plate of motor vehicles and their trailers).
In particular, an angle of incidence of at least 8° on the license plate is required, with the result that this angle can only be met with the above generic illumination device, if the projection is relatively large and the license plate is installed in the rear at a depth of about 7 cm. The angle of 8° is usually closely maintained structurally, since a larger angle would lead to an even greater depth.
Such a relatively large projection interferes with the design and can also act as a dirt trap and potentially adversely affect the cw value.
DE 10 2006 018 259 A1 does not disclose a solution on the vehicle body, but merely discloses a license plate holder with integrated illumination formed as a separate component, which is then suitably installed on the vehicle body. In addition, this reference discloses explicitly that the light generated by the respective LED is directed by a reflector specifically onto a light guide bar, wherein the light is then coupled from the light guide bar to a limited coupling surface in the light guide bar. In conjunction with a second embodiment, it is described that a predetermined light exit surface with an optical structure should be formed on the surface of the light guide bar facing away from the LEDs which directs light radiated by the LEDs towards the receiving plate. This optical structure is provided only in a central area of the light guide bar.
Furthermore, JP-A-2000168438 shows a structure in which the lamp housing is arranged completely inside a vehicle-body-side aperture.
DE 10 2005 028 694 A1 discloses a second reflector which serves only to direct the light emitted by an LED vertically downward in a manner illustrated therein in FIG. 8. A so-called diffusion step is provided as the only light-guiding or light-deflecting measure, which has the effect that light deflected downwardly by a first reflector is refracted again so that the upper partial area or upper edge portion of the license plate is illuminated.
DE 201 12 696 U1 only relates to a handle, in which a lighting fixture is integrated for license plate illumination. The light passes to the outside through a conventional window pane.
JP-A-2000 168 438 shows a structure in which in a vehicle-body-side aperture is provided in a horizontal body wall region directly above the license plate, through which a lamp protrudes from the inside to the outside in a technically unfavorable design. This lamp is sheathed by a U-shaped protective cover, wherein a light exit lens is provided at the bottom. U.S. 2009/019 60 59 A1 discloses a similar structure, having an aperture disposed in a cover through which light can be radiated onto the license plate. A diffusion lens is also provided which is arranged with spacing above the lens and which scatters the light downwards.
DE 40 13 503 A1 also relates to a completely different conceptual structure than described above. In fact, a housing projects here in the region of a projection downwards in the direction of the license plate, wherein a lens is inserted in the downward-projecting part. The design of such a structure is technically disadvantageous, causes unwanted high-frequency noise, and can act as a dirt trap.
DE 102 40 663 A1 also relates only to a license plate holder as such, in which LEDs are integrated in the edge.
DE 20 2005 014 363 U1 has a structure in which a lamp housing is clipped in a body-side projection and in the aperture formed therein. This lamp housing carries a light exit lens, above which an optical element is arranged directly below a lighting means that is intended to refract and scatter the light so that the entire license plate is illuminated.
DE 20 2006 009 627 U1 shows in FIG. 2 that a rear optical structure should be formed so that the light coming from an LED is deflected only vertically downwards.